Tirilazad mesylate is a novel nonglucocorticoid steroid compound that inhibits lipid peroxidation on the cell membrane. It has been shown to reduce the damaging effects triggered by brief periods of ischemia. It is intended to be used in patients following a stroke or a head injury. The liver is the principal site of Tirilazad metabolism, with metabolites of the drug excreted into the bile. Efforts to identify metabolites in feces have failed due to extensive biotransformation to a large number of metabolites and the instability of the metabolites. ERCP (endoscopic retrograde cholangio-pancreatography) is an endoscopic procedure used for diagnosis and treatment of the biliary and pancreatic ductal systems. It is a relatively non-invasive means of imaging the bile ducts, gall bladder and pancreatic ducts. Some patients who have had gall stones removed or a papillary sphincterotomy during ERCP have poor drainage of bile following the procedure. In these patients, a naso-biliary drain is placed for 24 hours to facilitate drainage of bile. A T-tube is commonly placed in the bile duct following surgical exploration to allow bile to drain easily during the initial healing period.